Lubricating oil compositions containing stabilized salt suspension



United States Fatent Q LUBRICATING OIL COMPOSITIONS CONTAININ GSTABILIZED SALT SUSPENSION Arnold J. Morway, Clark, N J., assignor toEsso Research and Engineering Company, a corporation of Delaware.

NoDrawing. Application October 24, 1957 Serial No. 692,041

11 Claims. or 252-405 This invention relates to lubricating oil.compositions containingcalcium acetate. Particularly,,it relatesto-lubricating fluids and greases comprising. lubricating oil, calcium.acetate, and a surface active agent for main.- taining the calciumacetate in a stable suspension.

Calcium acetate has been recently recognized as an extremely effectivelubricating oil additive for reducing wear and imparting'extremepressure characteristics to of. higher. molecular, weight salts. orsoaps result high:

deposit formation when the. lubricantisused as a crankcaselubricant;'whil e the emulsion type materials are rather corrosivebecause of their water content and are also somewhat unstable tendingto-separate upon-storage.

It has also been proposed to dehydrate the emulsion type i of material,but while this.- reduces the danger of corrosion, it; still. results inan unstable product and unless the dehydration is carefully controlled,va1 grainy unsatisfactory dispersion is obtained. I

It has now been found that calcium, acetate can be stably dispersed inlubricating oil in the presence. of. a surface active agent, preferablya non-ionic. or a cationic surface active agent containingpolyalkyleneoxy. groups.

Surface active agents. of. these types, .which. do. not .contain.

metal, have decreased tendencies. to. form. harmful deposits when usedin internal combustion engines. In this manner, excellent andstable-fluid lubricating dispersions suitable for crankcase use, can beformed. By increasing the amount of calciurnacetate dispersed.in,the'oil,.lubri-- eating greases. may. be formed whichareparticularlyuseful for lubrication of antifriction bearings operating atelevated temperatures: 1

The compositions of the invention will therefore comprise lubricatingoil, about 0.5 to ,50, e.g., 1.0 to 30 weight percent of calciumacetate, and about 0.05 to 10, e.g., 0.2 to 5 Weight percent of surfaceactive agent. All of said weight percents being based on thefinal-weightof the total composition. Generally, about'0;05 to*"1.0part'byweight of surface active agent per part by Weight of calciumacetatewill housed. v

The lubricating oilportion of the composition may be either. a minerallubricating oil, a synthetic lubricating oil,

. or both. Operable'synthetic oils include esters of dibasic' acids(e.g., di-Z-ethyl 'hexyl sebacate), esters of glycols (e.g., C19. oxoacid diester of tetraethylene glycol), complex esters (e.g., the complexester formed by reacting one mole of sebacic acid with two moles oftetraethylene glycol and two moles of 2-ethylhexanoic acid), halocarbonoils, alkyl silicates, sulfite esters, mercaptals, formals, polyglycoltype synthetic oils, etc.,or mixtures of any of the above in anyproportions. Although, the dispersed calcium acetate is more stable insynthetic ester oil than in mineral oil, even in ester oil the presenceof the surface active agent further improves the stability of thecalcium acetate dispersion and prolongsitsstorage stability.

The stabilizingagents which may be used include nonionic and cationicsurface active agents of the general formula:

wherein R is an aliphatic hydrocarbon radical having 2 to 4 carbonatoms, x is an integer of 5 to 200, e.g. 5 to 75, and y, which is either1 or 2 is the valence of R; and R. is a radical selected from the groupconsisting of:

wherein said R" is a straight or branched chain alkyl group containing 2to 30, e.g. 4 to 20 carbon atoms and may be derived from a fatty acid.

Where R represents R"O, the formula represents alkyl ethers ofpolyoxyalkylene'glycols. Specific examples include "-0 3H370( 5H When Rof the above formula is a hydroxyl group, specific examples of suchmaterials; will include polyoxyalkylene glycols such as. polyethylenevglycols and polypropylene glycols. A preferred type of these othermaterials are the copolymersiof ethylene and propylene glycols which arecommercially available under the trade-name of Pluronics. Thesematerials have the following formula: HO(C H;,O'),,(C,H O) (C H O) -H,where a and c are integers of value 2 to .150, and b is an integer of 5to 170. The molecular weight may vary considerably but generally isbetween 1,000 and 20,000, e.g. 1,000 to 10,000. Thus, Pluronic L-44,Pluronic L-62, and Pluronic F-68 appear to havemolecular weights ofabout 2800, 2300 and 8700 respectively. The ratio of the ethylene oxidegroups to the propylene oxide groups in the Pluronic materials varybetween about 3/1 to 1/3, e.g., in Pluronics L-62, analysis showed aratio of about 1.15 'molesof ethylene oxide per mole ofpropyleneoxide.However, the-ratio of these two alkyleneoxidegroups' is not critical forthe present invention since operablematerialswill include-ethylene orpropylene polyglycols per se.

- s Q Where R represents an R"-N radical, the formula represents N, Npolyalkyleneoxy disubstituted alkyl amines. Specific examples of suchmaterials will include:

CHzCHzO)H CnHwN I oHzomonH HaCHz )soH CuHsr-N (OHZCHzOhpH and omcmomomnCrsHs'r-N cmomcmomn A material of this general type, commerciallyavailable under the trade-name Ethomeen T/25, was used in several of theworking examples of the invention. This material V has the formula:

ene oxide groups is 15.

When R represents specific compounds will include and sHn

Surface active agents of the above general types are well known and areavailable under trade-names such as Ethomeens, Ethomids, Ethofats,Pluronics, etc.

Various other additive materials may also be included in thecompositions of the invention in amounts of about so a 4- 0.1 to 10.0wt. percent, based on the total weight of the composition. Examples ofsuch additives include oxidation inhibitors such as phenylalpha-naphthylamine, tackiness improvers such as polyisobutylene,corrosion inhibitors such as sorbitan monooleate, dyes, V.I. improvers,thickeners and the like. i

The lubricants of the present invention may be prepared by simpleblending of the surface active agent and preformed calcium acetate intoa lubricating oil. In this case, a small amount of water is desirable inorder to more thoroughly disperse the salt, the material then beingdehydrated to remove the water. However, a more preferable way is byforming the calcium acetate in situ in the lubricating oil byneutralizing lime or calcium oxide with acetic acid or acetic acidanhydride. When the lubricant is to be used at high temperatures, it ispreferably heated in order to achieve complete dehydration and to formthe anhydrous calcium acetate. The formation of the calcium acetate insitu is preferably carried out in the presence of the stabilizingmaterial or surface active agent, although the stabilizer can be addedlater. The lubricant may be homogenized in a Morehouse mill, a Gaulinhomogenizenetc. If a fluid lubricant is desired, it is generally moreconvenient to first form a concentrate and then to dilute it withadditional oil to form the final product.

The invention will be further understood by the following examples:

EXAMPLE I 17.0 parts by weight of hydrated lime, 2.0 parts by weight ofPluronics L-62 (copolymer of ethylene and propylene glycol having 2. molweight of about 2300 and a molar ratio of'ethylene oxide groups topropylene oxide groups of about 1.15), and 55.0 parts by weight of amineral lubricating oil SUS at 210 F.) were charged to a steam heatedgrease kettle and thoroughly mixed to a smooth, uniform slurry. 25 partsby weight of glacial acetic acid were then added slowly, the heat ofreaction raising the temperature of the mixture to about 220 F. Afterall the acetic acid was added, the material was then further stirred for15 minutes, after which external heating was applied until thetemperature rose to 320 F. to

completely dehydrate the mixture and form anhydrous calcium acetate. Theheat was then turned off and the product was allowed to cool to 200 F.while stirring.

One port by weight of phenyl-alpha-naphthylamine was then added, afterwhich the product was passed through a Gaulin homogenizer operating at6000 psi. shear.

EXAMPLE II 50 weight percent of the product of Example I was mixed with50 weight percent of additional mineral oil, after which the blend waspassedv through a Gaulin homogenizer operating at 6000 psi. shear.

EXAMPLE III 20 weight percent of the product of Example I was blendedwith 80 weight percent of additional mineral oil in the manner ofExample II.

EXAMPLES I-A, II-A AND III-A 'TableleGampasitionmud-properties ofexamples Example "I 'j. I-A II II-A III III-A "Composition:

Acetic Acid (Glaclal).. .-peroent.-- 25.10 25.0 12. 5 :12. 5 5. v 5.0Hydrated Lime :do. 17:0 17.0 8. 8. 5 3. 40' 3.4 Pluronics L-02 do 2.0v1.0 '0. 40

Ethozneen T/25 do 2; 0f 1. 0 0. 4 Phenyl-alpha-naphthylamine v.

(10.... 1. 0 1. 0 0. 5 0.5 0.20 '0. Mineral Oil (80:SUS'at 210'-F;)

"55. 0 55. 0 77. 5 77. 5 91. 00 91. 0 Properties: p R p AppearanceExcellent homogeneous Excellent homogeneous Fluid uniform ssmooth grease'smooth grease smooth fluid- Dropping Point F 500+ 500+ 500+ 5Penetration 77 mn1./10

Unworked 250 360 Worked 60 strokes 265 340 Worked 10,000 strokes 335Lubrication Life in Hours a (250 F.1,000 r.p.m.) 200 Four-Ball Wear Test(1,800

r.p.m.l0 Kg. Load-75 C.1 7 hour), Scar Spot dia. in mm 0. 25 0.26 AlmeuTest (Weights carried) Gradual Loading; 13

i Tallow-N (C H: C H30) H containing a total 01 15 oxyethylene groups.

3 Anti-friction Bearing Manufacturers-National Lubricating GreaseInstltute's test machine.

4 1400 SUS at 100 F. and 102 SUS at 210 F.

l 'lest still in progress.

As seen from.Table I, high dropping point greases which are structurallystable and fiuid lubricants can be prepared by varying the calciumacetate content. Both the grease and fluid lubricants had excellentload-carrying ability and gave low wear.

The fluid products of Example III and III-A were further tested forstability as follows: A sample bottle was filled with the lubricant andstored in an oven maintained at 210 F. for 48 hours, after which thesample was examined for salt precipitation. The products of Examples IIIand III-A both successfully passed the test, showing no precipitatedcalcium acetate. A simple dispersion of calcium acetate in oil, withoutthe surface active agent, showed considerable salt precipitation whentested in the same manner. It is thus seen that the presence of thesurface active agent stabilizes the calcium acetate dispersion.

To further illustrate the invention, Examples I, II, and III can berepeated but using in place of the Pluronics L-62, an equal weightpercent of any of the following:

( 1) Hexaethylene glycol 0 (CHaCHgO)g5H C1rHa1-C-N In summary, theinvention relates to lubricants containing calcium acetate (whichincludes anhydrous as well as hydrous calcium acetate) which may be thesole salt component of the composition, stabilized with a nonionic orcationic surface active agent, which contains no metal. Either greasecompositions containing about 10 to wt. percent calcium acetates orfluid lubricants containing 0.5 to 10.0 wt. percent calcium acetate maybe thus prepared. The use of higher molecular salts, e.g. calciumstearate or calcium petroleum sulfonate, is thereby avoided andlubricants having a lower overall metallic ash content can thus beformed.

What is claimed is:

1. A lubricating composition consisting essentially of a dispersion ofabout 0.5 to 50 wt. percent of calcium acetate in lubricating oil, whichis stabilized against calciurn acetate precipitation with about 0.05 to1.0 parts by weight per part by weight of calcium acetate of anon-metallic surface active agent selected from the group consisting ofionic and cationic surface active agents containing 5 to 200polyalkyleneoxy groups having 2 to 4 carbon atoms per group and havingat least one terminal hydroxy group in the molecule.

2. A lubricating composition according to claim 1, wherein said surfaceactive agent has the general formula:

wherein R is a C to C aliphatic hydrocarbon radical, .'x is 5 to 200, yis l to 2 and is the valence of R, and R is a radical selected from thegroup consisting of HO, R"O-, "-N R"COO, R"CON and wherein said whereinsaid radical.

9. A lubricating composition consisting essentially of lubricating oil,about 4 to 30 weight percent of anhydrous calcium acetate as the solesalt component and about 0.5 to 10 wt. percent of a stabilizing materialhaving the general formula: I

2 4 )41( 3 B )b( 2 4 )c'-' Surfacei agent. v,

wherein a and c are each integers of 2 to 150, b is an integer [of 5 to170 and the molecular weight is about 1,000 to 20,000.

10. A composition according to claim 9, wherein said oil is a mineraloil. v

11. A method of preparing the lubricating composition of claim 1, whichcomprises forming said calcium acetate in situ in said lubricating oilby neutralizing cal- References Cited in the file of this patent 1UNITED STATES PATENTS 2,019,051 Sullivan et a1. May 4, 1939 FOREIGNPATENTS 7 744,685 Great Britain Feb. 15, 1956 524,879 Canada May 8, 1956OTHER REFERENCES "Pluronics by Wyandotte Chem. Corp., Wyandotte, Mich.,pp. 1-4 (1952 publication).

1. A LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A DISPERSION OFABOUT 0.5 TO 50 WT. PERCENT OF CALCIUM ACETATE IN LUBRICATING OIL, WHICHIS STABILIZED AGAINST CALCIUM ACETATE PRECIPITATION WITH ABOUT 0.05 TO1.0 PARTS BY WEIGHT PER PART BY WEIGHT OF CALCIUM ACETATE OF ANON-METALLIC SURFACE ACTIVE AGENT SELECTED FROM THE GROUP CONSISTING OFIONIC AND CATIONIC SURFACE ACTIVE AGENTS CONTAINING 5 TO 200POLYALKYLENEOXY GROUPS HAVING 2 TO 4 CARBON ATOMSE PER GROUP AND HAVINGAT LEAST ONE TERMINAL HYDROXY GROUP IN THE MOLECULE.